SEA TS OF HE A T PROD UCTION. 



839 



following are some of his results, and also those obtained recently by 

 Rosenthal : 1 



CRAWFORD. 



Lean beef . . . = 0*740 



Hide of an ox with the hair - 0*787 



Lungs of a sheep . . =0*769 



Fresh milk of a cow . =0*999 



Arterial blood of a dog . - 1 *030 



Venous blood - 0*8928 



ROSENTHAL. 



Compact bone . . =0*300 



Spongy bone . . =0*710 



Fat . . . . =0*712 



Voluntary muscle . =0*825 



Defibrinated blood = 0*927 



It is to be noted that Davy, 2 Hillersohn, and Stein Bernstein 3 were 

 unable to find any marked difference between the specific heats of 

 arterial and venous blood. Recently Hale White 4 has made an in- 

 genious attempt to obtain the specific heat of a living warm-blooded 

 animal by experimenting upon a hibernating dormouse. His results 

 vary between 0*812 and 1*18, but they are only approximately accurate, 

 for the dormouse, even during hibernation, produces a small amount of 

 heat. 



Since all the tissues of the body contain a quantity of water, the mean 

 specific heat must be near unity, probably about 0*83. 



THE SEATS OF HEAT PRODUCTION. 



The work of Mayow (1674), Black (1757), Priestley (1772), 

 Lavoisier (1777), and Crawford (1779) 5 led to the conclusion that 

 animal heat was due to a process of combustion occurring in the body, 

 but concerning the chief seat of this combustion there was no unanimous 

 opinion. Mayow considered that the oxidation took place in the tissues 

 all over the body ; Crawford held that the heat was set free chiefly in 

 the capillaries of the body, owing, as he thought, to a difference in the 

 specific heat of arterial and venous blood ; Lavoisier was at first un- 

 decided, and considered that the heat arose in the lungs, and possibly in 

 other parts of the body, but finally he maintained that the lungs were 

 the chief seat of combustion. The theory of Lavoisier was contested by 

 Lagrange, 6 who maintained that if all the heat of the body were pro- 

 duced in the lungs, the tissues of that organ would be destroyed by so 

 high a temperature. This objection was for long held to be fatal to 

 Lavoisier's theory, until Berthelot, 7 by a careful calculation, showed that, 

 granting all the heat to be formed in the lungs, the temperature of those 

 parts would not be raised more than a minute fraction of a degree, 

 owing to the great volume of air and blood in the lungs and the rapidity 

 of the circulation, whereby the heat would be quickly distributed. 

 Moreover, Berthelot has shown by experiment that a small amount of 

 heat is formed in the lungs by the combination of oxygen with 



1 Arch. f. Physiol., Leipzig, 1878, S. 215. 



2 "Researches," London, 1839. 

 s Arch.f. PhysioL, Leipzig, 1896, S. 249. 



4 Journ. PhysioL, Cambridge and London, 1892, vol. xiii. p. 789 ; Croonian Lectures, 

 Lancet, London, June 19, 1897 ; Brit. Med. Journ., London. 1897, vol. i. p. 1653. 



5 Mayow, " Tractatus Quinque," 1674 ; Black, "Lectures on Chemistry," edited by 

 Robison, Edinburgh, 1803 ; Priestley, Phil. Trans., London, 1772, vol. Ixii. p. 147 ; 

 Crawford, "De Galore Animali," 1779 ; "On Animal Heat," 2nd edition, 1788 ; Lavoisier, 

 Brit. Acad. roy. d. sc., Paris, 1777. 



6 Hasseufratz, Ann. de chim., Paris, 1791, tome ix. p. 275. 



7 Compt. rend. Acad. d. sc., Paris, 1889, tome cix. p. 776. 



